1. Field of the Invention
The present invention relates generally to display systems for airplane cockpits or other vehicles, and more particularly, to a rear projection digital display system which allows a high level of information to be selectively displayed regarding such data as travel path, travel conditions, vehicle condition, geographical conditions, and hazard or obstruction warnings.
2. Description of the Related Art
The layouts of cockpits for airplanes are regulated by the FAA in the United States. The SAE (Society of Automotive Engineers), which acts as a standards writing/recommending body to the FAA, has issued standards for aircraft instruments which are adhered to in aircraft construction. For example, the 3ATI slot standard, which is an ARINC (Aeronautical Radio, Inc.) standard, has been complied with in the vast majority of all aircraft in use today. This standard was developed when electromechanical display devices, such as HSI (Horizontal Situation Indicator), were the norm, and only allows a panel area of 3".times.3" in dimension. With the advance of digital technology, there has been a need in the industry to replace these displays with digital versions, to provide increased reliability, accuracy and more functionality. However, these planes cannot be easily retrofitted with digital equipment that require a bigger screen, and the required 3.times.3 panel has conventionally proven to be too small for digital displays. The 3".times.3" display has been a major impediment to the development of such a digital display.
First, standard direct view LCDs are not mass produced in this size, and therefore a specially made LCD for 3".times.3" can cost as much as $10,000 each to produce. Furthermore, due to the construction of the direct view LCD, the outer perimeter of the device cannot be used to display information, as it is used by the drive electronics. As a result, the 3".times.3" LCD typically produces a display area of only 2.3".times.2.3".
This reduced display area impedes the ability to put enough information on the display for it to be useable for many functions.
A second problem addressed by the invention is the growing demand in the avionics industry for more sophisticated "situational awareness for safety" (SAS) technology. This refers to technology which provides the pilot with more easily understandable and more comprehensive information about the immediate surroundings, and any hazards which may be present.
For example, in 1996, there were 246 general aviation airplane crashes in the United States. Of these crashes, 42 were controlled flight into terrain (CFIT). That is, situations in which the airplane was flown into an obstruction such as a mountain, an antenna or the ground under control of the pilot. Typically these instances occur when visibility is very low and the pilot is off course. As a result, the pilot is unaware of the natural obstructions in flight path because the display devices only provide information on the desired flight course.
It is believed that if the present invention had been available for these planes, a large number of these accidents would have been prevented, and hundreds of lives saved. Thus, there is a need in the industry for (1) technology to effectively collect data on surrounding structures even when the pilot is off path, and (2) hardware to display this information in a simple and direct manner to the pilot, preferably using digital instruments.